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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2009-12-09 08:40:08 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 04:53:20 -0300
commit61f5db549dde43fb91a8b337f3a4096e4076c2d9 (patch)
tree0c28bb9dd1aab1b3fc8ce61036677a7790316421 /Documentation
parent2c0ab67be1b4197a4effac89bb0604832e38be8d (diff)
[media] v4l: Make v4l2_subdev inherit from media_entity
V4L2 subdevices are media entities. As such they need to inherit from (include) the media_entity structure. When registering/unregistering the subdevice, the media entity is automatically registered/unregistered. The entity is acquired on device open and released on device close. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/video4linux/v4l2-framework.txt23
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 062708169def..77d96f4e3f50 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -268,6 +268,26 @@ A sub-device driver initializes the v4l2_subdev struct using:
Afterwards you need to initialize subdev->name with a unique name and set the
module owner. This is done for you if you use the i2c helper functions.
+If integration with the media framework is needed, you must initialize the
+media_entity struct embedded in the v4l2_subdev struct (entity field) by
+calling media_entity_init():
+
+ struct media_pad *pads = &my_sd->pads;
+ int err;
+
+ err = media_entity_init(&sd->entity, npads, pads, 0);
+
+The pads array must have been previously initialized. There is no need to
+manually set the struct media_entity type and name fields, but the revision
+field must be initialized if needed.
+
+A reference to the entity will be automatically acquired/released when the
+subdev device node (if any) is opened/closed.
+
+Don't forget to cleanup the media entity before the sub-device is destroyed:
+
+ media_entity_cleanup(&sd->entity);
+
A device (bridge) driver needs to register the v4l2_subdev with the
v4l2_device:
@@ -277,6 +297,9 @@ This can fail if the subdev module disappeared before it could be registered.
After this function was called successfully the subdev->dev field points to
the v4l2_device.
+If the v4l2_device parent device has a non-NULL mdev field, the sub-device
+entity will be automatically registered with the media device.
+
You can unregister a sub-device using:
v4l2_device_unregister_subdev(sd);